I think that's Run for Your Money? VicViper confirm?
EDIT: Just google'd it. It's is indeed Run for Your Money! This game is a beast! Posted a 200%+ increase one week earlier this year, lol. At the rate it's going, it'll leg it out to 500k maybe.
I think it's something related to an anime that airs one time every three weeks, the week a new chapter is on tv, the sales have a big increase.